1. Field of the Invention
The present invention generally relates to portable telephone sets and data communication adaptors and, more particularly to a portable telephone set and a data communication adaptor used to build a mobile communication system that includes an information processing device.
Recently, portable telephone sets are being used not only for telephone communication but also used in combination with an information processing device for mobile communication. Accordingly, it is required that a portable telephone set be useful to build a mobile communication system.
2. Description of the Related Art
FIGS. 1A and 1B show a portable telephone set 10 according to the related art and how a mobile communication system is built using the portable telephone set 10.
The portable telephone set 10 has a connector 10a at the bottom thereof connectable to a connector of a cable.
FIG. 1A shows a mobile communication system 30 using an information processing device 20 not having a built-in data communication adaptor. The mobile communication system 30 is built using the information processing device 20, a cable 40 with connectors and a data communication adaptor 50. A connector 40a at an end of the cable 40 is connected to the connector 10a of the portable telephone set 10. A connector 40b at the other end of the cable 40 is connected to a connector 50a at an end of the data communication adaptor 50. The data communication adaptor 50 is inserted into a data communication adaptor accommodating unit 20a of the information processing device 20. A connector 50b at the other end of the data communication adaptor 50 is connected to a connector 20b at the rear end of the data communication adaptor accommodating unit 20a. 
Normally, the data communication adaptor 50 is inserted into the data communication adaptor 20a of the information processing device 20.
FIG. 1B shows how a mobile communication system 30A is built using an information processing device 20A having a built-in data communication adaptor. The information processing device 20A has a built-in data communication adaptor 60. The mobile communication system 30A is built using the information processing device 20A, the cable 40 with the connectors. The connector 40a at an end of the cable 40 is connected to the connector 10a of the portable telephone set 10 and the connector 40b at the other end is connected to a connector 60a of the data communication adaptor 60 built into the information processing device 20A.
A user who intends to perform mobile communication carries the portable telephone set 10 with himself or herself. In addition, the user carries the information processing device 20 (20A) and the cable 40 in, for example, a bag. If the cable 40 connected to the information processing device 20 (20A) is accommodated in the bag, a intensive force is applied to the joint between the cable 40 and the information processing device 20 (20A), causing the joint to be damaged. For this reason, the cable 40 is disconnected from the information processing device 20 (20A) while being carried.
Therefore, the user may leave the cable 40 behind at home since it is comparatively small. If the cable 40 is lost, mobile communication is impossible.
Another inconvenience is that, since the cable 40 should be connected to the portable telephone set 10 as well as to the information processing device 20 (20A), it takes time to build a mobile communication system.